POS0883 BIOPHYSICAL PROPERTIES OF MONOCYTES INDICATE DISEASE ACTIVITY, SEVERITY OF FIBROTIC OR MICROVASCULAR MANIFESTATIONS AND THE RISK FOR PROGRESSION IN SYSTEMIC SCLEROSIS
Authors: A. E. Matei, K. Markéta, L. Xu, A. H. Györfi, E. Boxberger, D. Soteriou, M. Papava, J. Prater, X. Hong, M. Kräter, G. Schett, J. Guck, J. H. W. Distler
Journal: Annals of the Rheumatic Diseases (2022)

Background Dysregulated immune responses are major pathogenic players in systemic sclerosis (SSc). The biophysical properties (such as cell deformation, Young’s modulus (a measure of cell stiffness) and area) of circulating immune cells reflect their states and functions, as well as their pathological activation (1-3). Thus, biophysical phenotyping can provide access to a novel, mostly unexplored layer of information that is currently not accessible with standard techniques of cellular and molecular biology. Real-time fluorescence and deformability cytometry (RT-FDC) is a novel technique that enables biophysical phenotyping of individual immune cells at a high throughput, which allows its use in a clinical setting (3-5). Objectives Here, we hypothesized that biophysical properties of circulating immune cells in SSc and rheumatoid arthritis (RA) might specifically reflect their distinct pathophysiological activation in the respective disease, and might indicate clinical outcomes such as disease activity or severity. We thus performed RT-FDC-based biophysical phenotyping of circulating immune cells in SSc, RA and healthy controls. Methods 63 SSc patients, 59 RA patients fulfilling the respective ACR/EULAR classification criteria and 18 age- and sex-matched healthy controls were included in the study between 05.2019 and 09.2021. Peripheral blood mononuclear cells (PBMC) were isolated and immunolabelled. PBMC subpopulations were identified in RT-FDC by standard gating strategies based on their marker expression and their deformation, Young’s modulus and area were determined. Results We identified SSc-specific changes (changes in SSc, but not in RA compared to healthy controls) in the biophysical properties of NK, NKT-like cells and monocyte subpopulations in SSc. Monocytes subpopulations had a higher deformation and cross-sectional area and/or more compact intra-donor distributions of these parameters in patients with active disease and with extensive skin or lung fibrosis in comparison with patients with stable disease and limited skin or lung fibrosis, respectively. All monocytes subsets were stiffer in patients with progression of skin of lung fibrosis at the time of measurement in comparison with a previous visit. The deformation and area of intermediate monocytes could also identify patients at risk for future progression of lung fibrosis. Changes in biophysical properties of monocytes can indicate, beyond fibrotic burden, clinical manifestations of microvascular damage such as active digital ulcers and pulmonary arterial hypertension. Conclusion We demonstrated that changes in the biophysical properties of monocytes subsets are associated with multiple clinical outcomes in SSc such as disease activity, severity of fibrotic or microvascular manifestations and risk of progression and might thus directly reflect SSc-specific pathologic immune cell activation. Our results thus provide first evidence that RT-FDC-based biophysical phenotyping of circulating immune cells may be a useful tool for clinical evaluation of SSc patients. References [1]Bashant KR, Toepfner N, Day CJ, Mehta NN, Kaplan MJ, Summers C, et al. The mechanics of myeloid cells. Biol Cell. 2020;112(4):103-12. [2]Toepfner N, Herold C, Otto O, Rosendahl P, Jacobi A, Krater M, et al. Detection of human disease conditions by single-cell morpho-rheological phenotyping of blood. Elife. 2018;7. [3]Kubankova M, Hohberger B, Hoffmanns J, Furst J, Herrmann M, Guck J, et al. Physical phenotype of blood cells is altered in COVID-19. Biophys J. 2021;120(14):2838-47. [4]Otto O, Rosendahl P, Mietke A, Golfier S, Herold C, Klaue D, et al. Real-time deformability cytometry: on-the-fly cell mechanical phenotyping. Nat Methods. 2015;12(3):199-202, 4 p following [5]Rosendahl P, Plak K, Jacobi A, Kraeter M, Toepfner N, Otto O, et al. Real-time fluorescence and deformability cytometry. Nat Methods. 2018;15(5):355-8. Disclosure of Interests Alexandru-Emil Matei: None declared, Kubánková Markéta: None declared, Liyan Xu: None declared, Andrea-Hermina Györfi: None declared, Evgenia Boxberger: None declared, Despina Soteriou: None declared, Maria Papava: None declared, Julia Prater: None declared, Xuezhi Hong: None declared, Martin Kräter: None declared, Georg Schett: None declared, Jochen Guck: None declared, Jörg H.W. Distler Shareholder of: JHWD is stock owner of 4D Science., Consultant of: JHWD has consultancy relationships with Actelion, Active Biotech, Anamar, Bayer Pharma, Boehringer Ingelheim, Celgene, Galapagos, GSK, Inventiva, JB Therapeutics, Medac, Pfizer, RuiYi and UCB, Grant/research support from: JHWD has received research funding from Anamar, Active Biotech, Array Biopharma, aTyr, BMS, Bayer Pharma, Boehringer Ingelheim, Celgene, Galapagos, GSK, Inventiva, Novartis, Sanofi-Aventis, RedX, UCB